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  <div class="section" id="cmake-minimum-required">
<span id="command:cmake_minimum_required"></span><h1>cmake_minimum_required<a class="headerlink" href="#cmake-minimum-required" title="Permalink to this headline">¶</a></h1>
<p>Require a minimum version of cmake.</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">cmake_minimum_required(</span><span class="no">VERSION</span><span class="w"> </span><span class="nv">&lt;min&gt;</span><span class="p">[...</span><span class="nv">&lt;max&gt;</span><span class="p">]</span><span class="w"> </span><span class="p">[</span><span class="no">FATAL_ERROR</span><span class="p">]</span><span class="nf">)</span><span class="w"></span>
</pre></div>
</div>
<p>Sets the minimum required version of cmake for a project.
Also updates the policy settings as explained below.</p>
<p><code class="docutils literal notranslate"><span class="pre">&lt;min&gt;</span></code> and the optional <code class="docutils literal notranslate"><span class="pre">&lt;max&gt;</span></code> are each CMake versions of the form
<code class="docutils literal notranslate"><span class="pre">major.minor[.patch[.tweak]]</span></code>, and the <code class="docutils literal notranslate"><span class="pre">...</span></code> is literal.</p>
<p>If the running version of CMake is lower than the <code class="docutils literal notranslate"><span class="pre">&lt;min&gt;</span></code> required
version it will stop processing the project and report an error.
The optional <code class="docutils literal notranslate"><span class="pre">&lt;max&gt;</span></code> version, if specified, must be at least the
<code class="docutils literal notranslate"><span class="pre">&lt;min&gt;</span></code> version and affects policy settings as described below.
If the running version of CMake is older than 3.12, the extra <code class="docutils literal notranslate"><span class="pre">...</span></code>
dots will be seen as version component separators, resulting in the
<code class="docutils literal notranslate"><span class="pre">...&lt;max&gt;</span></code> part being ignored and preserving the pre-3.12 behavior
of basing policies on <code class="docutils literal notranslate"><span class="pre">&lt;min&gt;</span></code>.</p>
<p>The <code class="docutils literal notranslate"><span class="pre">FATAL_ERROR</span></code> option is accepted but ignored by CMake 2.6 and
higher.  It should be specified so CMake versions 2.4 and lower fail
with an error instead of just a warning.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>Call the <code class="docutils literal notranslate"><span class="pre">cmake_minimum_required()</span></code> command at the beginning of
the top-level <code class="docutils literal notranslate"><span class="pre">CMakeLists.txt</span></code> file even before calling the
<span class="target" id="index-0-command:project"></span><a class="reference internal" href="project.html#command:project" title="project"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">project()</span></code></a> command.  It is important to establish version
and policy settings before invoking other commands whose behavior
they may affect.  See also policy <span class="target" id="index-0-policy:CMP0000"></span><a class="reference internal" href="../policy/CMP0000.html#policy:CMP0000" title="CMP0000"><code class="xref cmake cmake-policy docutils literal notranslate"><span class="pre">CMP0000</span></code></a>.</p>
<p>Calling <code class="docutils literal notranslate"><span class="pre">cmake_minimum_required()</span></code> inside a <span class="target" id="index-0-command:function"></span><a class="reference internal" href="function.html#command:function" title="function"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">function()</span></code></a>
limits some effects to the function scope when invoked.  Such calls
should not be made with the intention of having global effects.</p>
</div>
<div class="section" id="policy-settings">
<h2>Policy Settings<a class="headerlink" href="#policy-settings" title="Permalink to this headline">¶</a></h2>
<p>The <code class="docutils literal notranslate"><span class="pre">cmake_minimum_required(VERSION)</span></code> command implicitly invokes the
<span class="target" id="index-0-command:cmake_policy"></span><a class="reference internal" href="cmake_policy.html#command:cmake_policy" title="cmake_policy"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">cmake_policy(VERSION)</span></code></a> command to specify that the current
project code is written for the given range of CMake versions.
All policies known to the running version of CMake and introduced
in the <code class="docutils literal notranslate"><span class="pre">&lt;min&gt;</span></code> (or <code class="docutils literal notranslate"><span class="pre">&lt;max&gt;</span></code>, if specified) version or earlier will
be set to use <code class="docutils literal notranslate"><span class="pre">NEW</span></code> behavior.  All policies introduced in later
versions will be unset.  This effectively requests behavior preferred
as of a given CMake version and tells newer CMake versions to warn
about their new policies.</p>
<p>When a <code class="docutils literal notranslate"><span class="pre">&lt;min&gt;</span></code> version higher than 2.4 is specified the command
implicitly invokes</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">cmake_policy(</span><span class="no">VERSION</span><span class="w"> </span><span class="nv">&lt;min&gt;</span><span class="p">[...</span><span class="nv">&lt;max&gt;</span><span class="p">]</span><span class="nf">)</span><span class="w"></span>
</pre></div>
</div>
<p>which sets CMake policies based on the range of versions specified.
When a <code class="docutils literal notranslate"><span class="pre">&lt;min&gt;</span></code> version 2.4 or lower is given the command implicitly
invokes</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">cmake_policy(</span><span class="no">VERSION</span><span class="w"> </span><span class="m">2.4</span><span class="p">[...</span><span class="nv">&lt;max&gt;</span><span class="p">]</span><span class="nf">)</span><span class="w"></span>
</pre></div>
</div>
<p>which enables compatibility features for CMake 2.4 and lower.</p>
</div>
</div>


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